1. Field of the Invention
The present invention relates to a semiconductor device and a manufacturing method thereof.
2. Description of the Related Art
In recent years, object recognition technology which can be utilized for production, management, or the like by assigning IDs (identification numbers) to individual objects to reveal data thereon such as the history, has attracted much attention. Above all, semiconductor devices that can send and receive data without contact have been in development. As such semiconductor devices, RFIDs (Radio Frequency Identification) (also referred to as ID tags, IC tags, IC chips, RF (Radio Frequency) tags, wireless tags, electronic tags, and wireless chips) and the like are beginning to be adopted in companies, markets, and the like.
Many of these semiconductor devices each include an antenna, and a circuit (hereinafter also referred to as an IC (Integrated Circuit) chip) using a semiconductor substrate of silicon (Si) or the like, and the IC chip is made of a memory circuit (hereinafter also referred to as a memory), a control circuit, and the like. Further, the development of organic thin film transistors (hereinafter also referred to as TFTs), organic memories and the like using organic compounds in their control circuits, memory circuits and the like, is actively pursued (for example, Japanese Patent Laid-Open No. H7-22669).
However, in a memory circuit using an organic compound, in which a memory element is formed by providing an organic compound between a pair of electrodes, in the case where the organic compound layer is thick, the rise in a writing voltage becomes a problem depending on the size of the memory circuit. On the other hand, in the case where the size of the element is small and the organic compound layer is thin, the element is easily affected by dust or a projection and a depression on the surface of the electrode layers, which leads to a problem such as variations in properties of a memory (a writing voltage or the like) or abnormal writing.